Hydraulic power unit



June 2, 1953 s. B. MCLEOD HYDRAULIC POWER UNIT 2 Sheets-Sheet l FiledMarch 21, 1949 FIGJ.

uvwizvrox. STEWART B. McLEOD 7 w. Mk 8 7 4 \T 0 35 Q b 4 w a 5 a 3 u s FATTO RN EYS June 2, 1953 Y v s. B. MOLEODI 2,640,429

HYDRAULIC POWER UNIT Filed March 21, 1 949 2 Sheets-Sheet 2 INVENTOR.STEWART B. McLEOD- ATT RNEYS Patented June 2, 1953 HYDRAULIC POWER, UNITStewartB; McLeod; Dearborn, Mich-., assignor to Detroit. Harvester.Company, Detroit, Mich a corporation of. Michigan Application March 21,1949, SerialNo. 82,529

2- Claims.

The present invention relates to: a hydraulic power unit and moreparticularly to a combined pump; motor, reservoirand controlvalves-therefor.

Th present invention. is capable of general application but may be usedin the type of systern disclosed in my prior Patent 2,388,755, grantedNovember 13, 1945;

This application is a continuation in part of my co-pending application,Serial No. 776,635, filed September 29,v 1947, now Patent No. 2,588,644.

In accordance with the present invention, a hydraulic system including'areversible pump is provided with a by-passand reservoir connec tion unitwhich serves to seal the pressure side of the pump and open the suctionside of the pump to the reservoir to compensate for unequal volumes offlow due to piston rod displacement when the cylindersare used. In oneembodiment of the present invention the mechanism is further constructedto afford pressure relief so as to prevent development of excessivepressuresat the pressure side of the pump. Inasmuch as in thepresentconstruction the fluid flow is not through th unit to thecylinders or fluid motors, th unit can be made without regard to flowareas through the valve and consequently may be relatively small andinexpensive.

It is an object of the present invention to provide an improvedhydraulic power unit characterized by its efficiency, extremesimplicity, the compactness of its arrangement andthe economy with whichit may be produced.

More specifically, it is an object of the present invention to combine apump, motor, reservoir and control valves for supply fluid in a novelarrangement whereby a hydraulic system in which said unit is connectedremains always fully charged with fluid.

It is a further object of the present invention toprovide areversible-pump and reservoir unit in which the reservoir is connectedat all times during operation of th pump to the suction side thereof.

It is a further object of the present invention to provide a by-passconnection for a reversible pump which remains open when the pump isidle to provide for manual, operation of normally fluid operatedmechanism but which is closed by operation of the pump in eitherdirection.

It is a further object of the present invention to provide a by-passbetween the pressure and suction sides of a pump adapted to remain openwhen the pump is idle, to close during normal pump; operation, and toreopen in the event of excessive pressure at the pressure side of thepump.

It is a feature of the present invention. to. provide a hydraulic powerunit comprising a; block having a recess therein for the reception of arotary pump, a motor supported from the block in driving relation withthe pump, passages for circulating fluid communicating at oneside of therecess with opposit sides of the pump, a fluid supply reservoir carriedby the block having passages communicating at the opposite side of therecess with opposite sides of said pump, and valves for controlling the.flow of supply fluid between the reservoir and" pump.

Other objects and features of the invention will become apparent as thedescription proceeds; especially when taken in conjunction with theaccompanying drawings, wherein:

Figure 1 is an elevation, partly'in section, of my improved unit;

Figure 2 is a section on the line 2-2 of; Figure 1;

Figure 3' is a section-on the line 33 of, Figure 2;

Figure-4 is a perspective view of the valve enga-gingelement employed inmy improved construction;

Figure 5 is'a section on the line- 5-5 of'Figure 1;

Figure 6 is a fragmentary section on the line 6-6, Figure 5;

Figure '7 is a vertical elevation, partly in; section, of a somewhatdifferent embodiment of'the present invention;

Figure 8, is a section on the line B--8' of Figure Figure 9 is. anenlarged fragmentary section on the line 9-9 of, Figure8.

Thepresent construction comprises a block 0 carried at the top of amotor housing 30: and. supporting at its upper surface a fluid supply beappreciated that the device illustrated is for 3 use in supplying fluidto a hydraulic system and that the system will include conduits havingthreaded connectors cooperating with the connecting portions I5 and I5.Passages I3 and M serve as inlet and outlet connections to the pump,depending upon the direction of rotation thereof. In other words, thpump is reversible and in one instance fluid will be drawn in throughthe passage I3 and discharged through the passage I4, whereas when thepump is rotated in the opposite direction, the direction of flow of thefluid is reversed.

Th block I0 is provided with an opening I! the-rethrough which iscoaxial with the cylindrical recess II and which receives the driveshaft I8 of an electric motor indicated at I9. The lower end of theopening I? is enlarged to receive a suitable seal and bearing for theshaft I8.

The motor I9 is carried'within the housing which is assembled to theblock III by means of long attaching screws 32 threaded into tappedrecesses in the block I!) as indicated at 33. A conductor for supplyingpower to the motor I9 is illustrated at 34.

Located on the upper surface of the block I0 is the reservoir 40. Asillustrated, the reservoir may be in the form of a sheet metal cuphaving a removable closure 4L The bottom 42 of the reservoir 40 isprovided with a circular opening 43 surrounding the rotor IZa, and asealing gasket 44 is provided between the bottom 42 and the uppersurface of block I0.

Located within the reservoir 40 is a valve which serves to provide andcontrol fluid supply passages between the reservoir and the pump. Afirst passage 5| communicates with a short, relatively small transversepassage '53 formed in the central portion of a boss 54. At its outerends the passage 53 communicates with enlarged end passages or openingsand 56. Intermediate the passage 53 and the two enlarged end openings 55and 56 are conical valve seat portions 51 and 58, respectively. Locatedwithin the enlarged opens 55 and '56 are ball valves 59 and 60,respectively. The outer ends of the openings 55 and 56 are closed bythreaded plugs BI and 62, respectively, and intermediate the plugs BIand 62 and the ball valves 59 and are balancing springs I53 and 64,respectively. Extending laterally from the enlarged openings 55 and 56are ports and 65 which communicate with the side of the gear pumpopposite to ports or passages I3 and I 4.

Intermediate the ball valves 59 and 60 is a slidable element 81, shownin detail in Figure 4. The element 61 may conveniently be formed ofmetal of triangular cross section and preferably has rounded corners, asindicated at 69. The element 6'! is slidably received in the passage 53but byvirtue of its triangular cross section it permits flow of fluidthrough said passage 53.

The element 61 is of such length that when the ball valves 59 and 6B aresymmetrically located with respect to their seats 51 and 58,

respectively, both valves are in partially open position. On the otherhand, it will be readily apparent that when one of the ball valves 59 or60 closes by virtue of pressure existing in the passage with which itcommunicates, the other of the ball valves is mechanically moved to fullopen position.

Springs 63 and 64 areof substantially equal strength so that in theabsence of pressure in 4 the device the ball valves stand in theposition shown in Figure 1.

The assembly of the parts includes the use of assembly bolts 12 (Figure2) which extend through the valve body 50 into suitably tapped openingsformed in the upper surface of the block ID.

The cover or closure 4| for the reservoir 40 is illustrated as securedin place thereon by means of a tie bolt III threaded at its lower endinto a suitably tapped recess 10a in the upper surface of the valve body50 and provided at its upper end with a nut II.

Th under surface of the valve body 50 rests directly on the uppersurface of the pump comprising the gear members I2a and I2b and thusconstitutes the upper closure for the pump chamber, the lower portion ofwhich is constituted by the cylindrical recess II formed in the uppersurface of the block I D.

The valve body 50 is provided with a transverse passage I3 whichcommunicates with an opening 14 provided in the gear member I2?) andwhich permits flow of oil therethrough to relieve prese sures whichmight otherwise build up. The gear I2b is provided with a keyway I5which receives a driving ball or key I6 seated in a recess at the end ofthe drive shaft I8.-

An oil slinger I8 is carried by the shaft I8 below the bearing structure20 and any oil which passes downwardly of the shaft below the bearingencounters the oil slinger and is thrown thereby in radial direction.The attaching bolts 32 which connect the motor to the block I0 areprovided with oil resistant rubber sleeves I9 which serve to sealpassages through which the bolts 32 extend.

The mounting means for the assembly comprises a ring III) to which issuitably secured a bracket II2 having ears H3 provided with openings I Mwhich receive rubber mounting bushings II5. In order to prevent rotationof the motor, pump, valve and reservoir assembly relative to themounting ring I I8, a recess H6 is provided on the upper surface of themotor housing and a portion of the ring H0 is lanced inwardly to form afinger IIB which seats in the recess H6 and thus serves as a positivemeans for preventing relative rotation between the ring I In and theremainder of the assembly.

If desired, a similar finger may be provided at the upper edge of thering I I0 and may cooperate with a correspondingly formed recessprovided at the under side of the block I 0. This will serve theadditional function of positively preventing even slight relativerotation between the motor (and hence the gear pump members I 2a andI212) and the block I0 and associated structure. Moreover, since thefastening elements 32 are adapted to draw the motor assembly toward theblock III,-

they will insure positive clamping of the ring between these elementsand will contribute to the rigidity of the structure as well as theproper alignment of the motor shaft in the block III.-v

In addition to serving as means for mounting the unit, the ring I I 0serves as a closure member for the space between the top of the motorand the under side of the block I0. The top of the motor has a circularboss I 20 recessed at diametrically opposite-points I 2| to receivescrews 32 and sleeves 79. Outwardly from the boss I29;

there is provided an annular seat I22 which receives the lower edge ofthe ring I II]. A plurality; of recesses H9 are provided in the loweredge of v the ring and cooperate with the upper-surface.

of the motor assembly to provide passages which" permit the escape ofoil or hydraulic fluid which might otherwise accumulate within thespace.

In order to prevent leakage of fluid from the reservoir 40, which mightotherwise occur due to motion of the vehicle or inclination of thevehicle, the cover 4!- is provided with an annular sealing ring ofinverted U-shape cross section indicated at H5 in Figure l. Thecover 41has a correspondingly shaped downwardly opening groove H6 cooperatingwith the sealing ring H5 and beneath the groove N6 the cover 41 has adownwardly and outwardly flaring flange '8. This construction provides afluid tight seal at the juncture between the cov- 61' 4| and thereservoir 40. 1

In use the cover M is clamped downwardly against the top of thereservoir 40 by means of the nut H threaded to the upper end of the boltID. A seal is also provided where. the bolt 10 passes through an openingI in the cover 41. This seal comprises a suitable resilient gasket I22which may be formed of an oil resistant rubber or the like and which isreceived in a downwardly flaring cup I2 1. The gasket I22 is in itsuncompressed condition somewhat larger than the cup I24. Accordingly, asthe nut II is tightened down and the material of the gasket I22 iscompressed, it is forced by the cup I24 to expand inwardly and thus tomakea fiuid tight seal with the upper surface of the cover 41: and withthe upper portion of the bolt Iii. By this construction the reservoiris, rendered fluid tight and the possibility of fluid. spilling orleaking therefrom in use is completely avoided. The sealed constructionof the reservoir is rendered possible due to the fact that the entiresystem in which the power unit is included is a closed system.

The operation of my improved device is believed to be readily apparent,especially when taken in consideration with the full discussion of myprior construction contained in Patent 2,388,755 and my co-pendi'ngapplication Serial No. 776,635, now Patent No. 2,588,644,. of which thepresent application is a continuation in part However, for completeness,it may be noted that upon the establishment of pressure by operation ofthe pump in the circulating fluid passage I4, pressure willsimultaneously be established within the enlarged opening 56 and willclose the valve it. At this time suction is established in the passageI3 at the opposite side of the block I0 and also in the opening 55. Atthisv time, since the ball. valve 60 is forced. on its seat by pressure,the ball valve 59 is in fully open position, thus establishingcommunication between the interior of reservoir and the suction side ofthe pump. As a result of this, and in the event that the demand forfluid in the pressure side of the circulating system is more than can besupplied from the suction side thereof, the difierence in fluid requiredis made up by withdrawing fluid from the reservoir, as will be readilyapparent.

Another valuable function of the balanced arrangement of ball valves isserving as a bypass around the pump. Thus where the unit is employed asa power unit for raising and lowering a convertible top, or other use,the balanced valves provide for a limited by-pass flow of fluid aroundthe pump, and permits manual operation of the operated device. In thiscase flow of fluid is in one direction or the other through thefollowing sequence of passages:

passage I4, the pump, passages 56-553., 65, theother side of pump, andpassage 1.3. Slow man ual operation is permitted, whereas rapid operation with corres onding rapid flow of fluid through thevalved'passages will close one the other of the ball valves, dependingon the direction of flow.

Referring now to Figures 7 to 9, there is the hydraulic power unitcomprises a motor housing 80, a block 8I- serving as the support for apump 82 including pump gears I03 and H14, a reservoir 8-3 and a by-passand reservoir connection unit indicated generally at 84. With theexception of the by-pass and reservoir connection unit 85, theconstruction of this embodiment may be identical with that illustratedin Figure 1 and will therefore not be described in detail.

However, the by-pass and reservoir connection unit 34 provides theadditional function of affording pressure relief in the event ofattainment of excessive pressures at the discharge side of the pump 82.

The unit 84 is provided at its ends with enlarged chambers 35 and 86closed by threaded plugs 87 and 88, respectively. Intermediate thechambers and 85 is a passage 89 of reduced diameter forming at itsopposite ends valve seats 90- and 9|. A reservoir passage 92 ex.- tendstransversely from the unit 8 into the interior of the reservoir 83 andcommunicates with the reduced passage 89' intermediate the valve seats90 and 91. Valve elements Stand 94 are provided adjacent the valve seats9'0 and ill, each or these valves being provided With'a central port Q5,as'best illustrated in Figure '7. The valves 93 and 9d are ofnon-circular shape and are illustrated in Figure 9 as being hexagonal soas to provide for flow of fluid through the reduced passage either fromend to end or from one end to and through the transversereservoirpassage 92. The ends of the pin 96 are provided with reducedextending portions 91- which are herein illustrated as conical and beingof a diameter at their base substantially equal to the diameter of theport 535 formed in the valves. Intermediate the projecting end portions91', the pin 95 is of somewhat larger diameter than the ports 95 formedin the valves so that when said valves are retained against the enlargedin-- termediate portion of the pin 96 as by spring pressure, the ports95 are closed.

Balancing spring means are provided and take the form of compressionsprings 98 engaging the ported valves 93 and 94 at one end and seated atthe other end against the plugs 81 and 88, these plugs being providedwith centering projections 99 to retain the springs in centeredrelationship.

Means are provided for connecting chambers 85 and 86 to opposite sidesof the pump 82 and these means take the form of passages NH and I02extending transversely from the chambers 85 and 86 respectively, andcommunicating with the internal and external gear members of the pump82.

The operation of this embodiment of the invention is similar to that ofthe embodiment i1- lustrated in Figure 1. When the pump is idle thesprings 98 retain the pin 96 in centered position' and the valves 93 and94 are bothre tained away from their corresponding valve seats 90 and9|. At this time a by-pass is open between opposite sides of the pumpcomprising the passage ll, chamber 85, reduced passage 89, chamber 86and passage I02. By virtue of-this arrangement a by-pass flow of fluidis permitted when the pump is idle. Therefore, the mechanism to whichthe pump is connected may be operated manually.

If now the pump is started in either direction pressure will build up atthe pressure side thereof which communicates with the chamber 85 or 86and this pressure will force the valve 93 or 94 onto its correspondingvalve seat, thus closing the by-pass passage. However, closure of eithervalve 93 or 94 results in further opening of the other valve, therebymaintaining open the passage connecting the suction side of the pumpwith the interior of the reservoir to permit flow of fluid to or fromthe reservoir to compensate for unequal flow of fluid to and from thehydraulic motor.

If an excessive pressure is built up in either the chamber 85 or 86 as aresult, for example, of interference with the normal operation of adevice actuated by the hydraulic motor, the bypass connection betweenopposite sides of the motor is again opened. This is accomplished byvirtue of the pressure acting against one end of the pin 96 through theport 95 in the chamber subjected to the high pressure. When thispressure exerts a force sufiicient to overcome compression of the springopposing movement of the pin 96 away from the valve subjected to theexcessive pressure, the pin 96 moves bodily away from said valve andthereby opens the port 95 in the valve. Accordingly, by selecting thestrength of the balancing springs 98, the maximum pressure which thepump 82 will deliver may be determined.

It is emphasized that the present construction represents a substantialimprovement over my prior construction, particularly as to compactness,simplicity of mounting, efficiency of operation and the economy withwhich the construction may be produced.

The drawings and the foregoing specification constitute a description ofthe improved hydraulic power unit in such full, clear, concise and exactterms as to-enable any person skilled in the art to practice theinvention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. In a hydraulic power unit, a pump housing block having a circularpump recess in its uptom wall having a circular opening thereininregistration with said circular recess and forming an upward extensionof said recess, the upper surface of the bottom wall of said reservoirbeing coplanar with the upper surface of said pump gears, a valve bodyin said reservoir having a fiat under-surface resting upon thebottomwall of said reservoir surrounding the opening.

therein, the under-surface of said valve body constituting a closure forthe upper end of the pump recess, fluid passages in said valve bodyterminating in ports at the under-surface of said body communicatingwith said pump recess,

valves in said body controlling the flow of fluid to and from saidreservoir, and fastening means assembling said piunp housing block,reservoir, and valve body comprising fastening elements extendingthrough said valve body and the bottom wall of said reservoir laterallyoutwardly from said pump recess into said pump housing block.

2. Structure as defined in claim 1 which comprises a removable top coverfor said reservoir,-

and means for securing said cover in place on said reservoir comprisinga rod carried by said valve body and extending upwardly therefromthrough said reservoir, and means on said rod engaging said cover.

STEWART B. MCLEOD.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 326,345 Taylor Sept. 15, 1885 1,185,639 Dunlap June 6, 19161,711,752 Seipt May 7, 1929 1,869,835 Alexander et a1 Aug. 2, 19322,023,039 Wells et al Dec. 3, 1935 2,062,045 Van Deventer Nov. 24, 19362,067,348 Schaumann, Jr Jan. 12, 1937 2,107,630 Erbach Feb. 8, 19382,135,881 Wentworth Nov. 8, 1938 2,222,203 Manseau Nov. 19, 1940'2,272,926 Squiller Feb. 10, 1942 2,312,686 Campbell Mar. 2, 19432,451,799 Brown Oct. 19, 1948 Curtis et al Feb. 6, 1951

